The Weather Outside is Frightful
Cold Weather Running
by Randall J. Brown, MHS, PT
From time to time one might ask themself: Would I rather freeze to death or roast to death? My answer seems to vary predictably with the season. In the winter, the last thing I want to do is to freeze to death. Read on and you'll understand why. You'll also learn how to protect yourself from the cold while you're running outside. In short, this article may help you to survive if you don't know Jack.... Jack Frost, that is.
Where's the Thermostat?
- Humans as Homeotherms -
We humans must maintain our body's core temperature within relatively narrow limits in order to stay alive (75-105 deg. F). Your intelligent body wants to maintain its core temperature as close to your 98.6F (37C) set point as it can. Therefore, when your body is confronted with cold temperatures, it will shunt blood towards the core and away from the extremities by constricting blood vessels (vasoconstriction) in your limbs. Your body produces heat internally in several forms: biochemical reactions (basal metabolism), by shivering, and by vigorous activity.
Can You Say Hypothermia?
- The Dangers of Getting too Cold -
We know from experience that moderately cold environmental temperatures enhance performance. Severely cold temperatures can adversely effect our performance though, and prolonged exposure to the cold can be deadly if hypothermia (the lowering of our core temperature) occurs. Unlike acclimatization to the heat, the human body has no adaptive ability to the cold except for mental tolerance. Risk factors include people with low body fat, poor nutrition, dehydration, and alcohol use. Hypothermia is categorized as mild, moderate or severe.
- Mild - Core 90-97F - uncontrollable shivering; decreased fine motor skills and cognitive function; amnesia Moderate - Core 85-89F - shivering stops; irrational behavior; grossly uncoordinated movements; somnolence
- Severe - Core below 85F - no pain response; loss of reflexes; coma; significant hypotension
The lowest adult hypothermia survival is 60.8F
Be aware that hypothermia can set in rapidly after you stop running. Your heat production engine has stopped but the loss remains high. It is therefore important to find shelter and to get into some dry clothes as soon as possible.
The Hazards of Frostbite - What Bit Me?
Think for a moment about a cold wind on you exposed skin and the effects of vasoconstriction of blood vessels supplying your extremities. Remember that your body wants to keep its core and vital organs warm and, when push comes to shove, your torso frankly couldn't care less about the comfort your hands and feet. The reduced blood flow to your extremities coupled with very cold temperatures can lead to actual freezing of your fingers, toes, ears and nose. Even more alarming, once the area is numb from the cold, you probably won't even feel the damage as it's occurring. True frostbite is an irreversible loss of tissue. Let's categorize this cold injury in two ways:
Freeze-thaw-refreeze and cold water immersion followed by freezing have very poor prognoses.
- Superficial - termed "frost nip"; it is a reversible condition involving skin surface only. The skin is numb, waxy and white but without blisters.
- Deep - Deep purple blisters appear. You are in trouble. The bone may freeze. Amputation may be required.
Practical Practices for Running in the Winter Prevention of Cold Injury
- Reducing your heat loss to the environment takes careful judgement.-
About Randy Brown
- Layer your clothing - Resist the temptation to overdress, as excessive sweating under too many layers may result in your getting really cold during the run - especially if you have to stop or slow way down or you find yourself running into a headwind. Best fabrics to wear - The best fabrics for cold weather running are those that have high insulating properties that are not diminished significantly by wetting. These fabrics include Polypropylene, wool, wool/synthetic blends, and treated polyesters like Capilene. The fabric closest to your body should wick moisture away from your skin. Avoid wearing cotton. It has poor insulating ability, which decreases even more when it becomes wet. Wind protection - It is essential that you wear an outer layer of Gortex or nylon for cold weather running. This includes top, bottom and hood. Vaseline on any exposed skin is helpful if it is not severely cold weather. Covering miscellaneous body parts
Avoid Getting Wet - Soaked clothing from things like rain showers and nearly frozen rivers can lead to some serious problems. Gortex will protect you from rain. Avoid bodies of cold water - especially if you're clumsy. Consider wind chill - Like considering the humidity and temperature for a summer run, you must account for the wind and temperature for running in the winter. This refers to both natural wind and the air movement created if you are running fast. Warm-up properly - As you probably know, it's hard to warm up when you're freezing cold. The key is to do your stretching while you're inside, then to wear heavier clothing outside until you warm up, at which time you shed your layers down to the right amount for the current weather conditions. Run into the wind on the way out - Try to avoid running into a headwind on your way home when you are sweaty and tired. Stay hydrated - Although it's cold, you will continue to sweat while you're exercising. Under several layers of clothing, you may not realize how much you are sweating. Also, in very cold weather the humidity approaches zero, and large amounts of fluid are lost through exhaled vapor. Stay nourished - During long runs in the winter, plan on eating snacks at regular intervals. Good nutrition is necessary for prolonged muscular activity. Seek medical help for hypothermia and frostbite - Get to a hospital if you become more than mildly hypothermic.
- Wear a cap! Everyone knows that you can lose a lot of heat through radiation from your head. Well-vented ski goggles can be worn. Be careful of wearing contact lenses in extremely cold weather - they can freeze to your eyeball. Polypropylene gloves and maybe Gortex or nylon mittens are important to protect your hands. Consider wearing two pairs of socks - an inner polypropylene pair and an outer wool pair. Size your winter running shoes appropriately. Since trunk cooling leads to vasoconstriction in your extremities, you should adequately insulate your trunk in order to help keep your hands and feet warm.
- Men may want to wear some briefs with strategically placed insulation to maintain comfort during and after your cold weather outing.
- Considerations for asthmatics - When the temperature differential between the ambient air and our lungs is large (over 100 degrees F), the air entering the lungs cannot be fully warmed or humidified. This can cause a reactive bronchospasm even in normal subjects. Asthmatics should be particularly aware of this risk. Bronchodilators can be helpful when used prophylactically before your run.
Currently doing his best to stay warm while working as a physical therapist at the University of Virginia in Charlottesville, Randy has been both a competitive and recreational runner since 1974. He competed through high school in Chico, California, and college at the U.S. Merchant Marine Academy in Kings Point, NY, and at the corporate level for General Electric. He has coached cross country at the College of Charleston, was a 3-term president of the Charleston Running Club, and the company physical therapist for the Charleston Ballet Theatre. Randy is also a licensed massage therapist and a former engineer.
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